Daniel Anderson is busily growing a vegetable garden full of tomatoes, peppers, cucumbers, radishes, parsnips and purple cauliflower – that last one for fun. During the fertile summer months his family feasts on his offerings, rarely having to look outside the garden for their five a day. He waters his vegetables from a rainwater butt and uses only hedgehog-friendly slug pellets.

Fiona Anderson is a stickler for keeping the heating down. When it’s cold, she tells the chillier Andersons to put on another jumper rather than crank up the boiler; she sighs at other family members’ profligacy as she goes around the house turning lights off.

Fiona and Daniel may sound like thrifty parents trying to encourage good green habits among their young, but Fiona, 10, and Daniel, 12, are brother and sister. They are members of the younger generation, for whom sorting rubbish into recyclable and non-recyclable items, and saving batteries rather than binning them, comes naturally.

Fiona has just put her father’s jeans to good use by turning them into a school bag, using old curtain tie backs as handles. “When you learn about rubbish being thrown into the ground, and that wildlife needs our help, it just makes you want to do something about it,” she says.

We older folks, brought up and educated before the words greenhouse effect or carbon emissions meant anything, may be struggling with the concept of reducing consumption and waste. But for a new generation of children, whose primary and secondary schools have instituted Green Clubs and Eco-Action Committees and who have even seen children’s staple Blue Peter screen its Green Peter specials, turning off the tap while brushing teeth and switching off the television standby is par for the course.

St Lucia’s Primary School, in Shrewsbury, for example, got parents and children involved in a project that recycles 98 per cent of its waste. A lot was saved by getting parents to think about lunch packaging. Sibford School, in Oxfordshire, saved a huge amount during a ''Switch Off’’ fortnight when electricity use dropped by a quarter. Dozens of schools now grow their own vegetables for school dinners. Children in these projects then bring the message home.

“Daniel is really serious about growing his own food,” says his mother, Julia, who has let him dig up part of the lawn at their Blackburn home this year to expand his plot.

“I’m a child of the Sixties,” says IT project manager Paul Kelly, from Witheridge, in Devon. “We didn’t think about where our resources came from. I’ve just fitted an aerated head onto the shower to reduce the flow of water, after pondering it for ages. But for the kids it just comes naturally – after dinner they automatically put scraps into the compost.” Paul’s daughter Margaret, eight, is also becoming green fingered and, like Daniel Anderson, is a member of the National Trust’s Sowing Squad – a group of 13 youngsters keen to spread the word about the pleasure of growing one’s own food.

The Strange children, from Horsham, in Sussex, are very good at policing their parents, says mother Jackie. “I’ve got three boys and they like to be dramatic about things. They tell me that if we drive to school rather than walk the world’s going to get too hot and we’re all going to die. My eldest, Ben, is just starting to become aware of the massive amounts of waste we create and he’s starting to ask why.”

Ben, aged nine, cultivates onions, potatoes, carrots and lettuce at home, and weeds the garden after doing his homework. He is especially annoyed about food packaging.

The ''older young’’ in their twenties and thirties have been accused of being politically apathetic, not voting or protesting in the same numbers as their parents and grandparents did. Maybe it will be down to the current younger generation of under-15 year-olds who will really want to make a difference. Let’s hope it won’t be too late.

For information on the National Trust’s food campaign, and details of events where the trust is giving away free seeds for thyme, salads and carrots, visit www.nationaltrust.org.uk/food